The use of naturally derived material as starting materials and intermediates for commercial products is a growing industry. For example, a great deal of research is being conducted to convert natural products into fuels as a cleaner alternative to fossil-fuel based energy sources. Agricultural raw materials such as starch, cellulose, sucrose or inulin are inexpensive and renewable starting materials for the manufacture of hexoses, such as glucose and fructose. Fructose, an abundant compound derived from natural products such as corn, may be converted to other materials, such as hydroxymethylfurfural, or HMF, and its related ethers.

One desirable derivative of HMF ethers is a partial reduction product which converts the aldehyde moiety of HMF to an alcohol. Although there is no known method for the reduction of HMF ethers, one method of reducing aldehydes to alcohols is described by Eller et al. in U.S. Pat. No. 6,350,923. This method uses a metal catalyst, such as nickel, cobalt or copper, reacted with the aldehydes at elevated temperatures and pressures. However, the method does not mention the ability of the catalyst to reduce a C═C bond.
Methods used to synthesize products that are similar to HMF ethers are also inadequate in terms of yield and use of undesirable reactants. For example, a method of synthesizing an equivalent of an HMF ether derivative without the use of HMF as a starting material is described by Pevzner et al. (Zhurnal Organicheskoi Khimii (1987), 23(6), 1292-4). In this method, an alkyloxymethylfuran is reacted with paraformaldehyde at 70-80° C. for 3 hours to give 2-hydroxymethyl-5-alkyloxymethylfuran. However, the yield was poor 55%, and in addition, the reaction requires the use of paraformaldehyde, a known irritant to the respiratory system and skin.
The product guide for G-693 nickel on kieselguhr with zirconium promoter catalyst (Sud Chemie) lists the catalyst as useful for reduction of terpenes, which contain C═C bonds. However, as is well known in the art, the furan ring in HMF, which contains two conjugated C═C bonds, is much more difficult to reduce than non-conjugated C═C bonds. Furthermore, the guide does not mention the ability of the catalyst to reduce aldehydes.
The present disclosure addresses the shortfalls of the prior art and provides methods for reducing the aldehyde and/or C═C bond of HMF ethers to the resulting alcohol and C—C bond, respectively, at high yields.